MetaRuby contains miscellaneous libraries (useful now) for a future Ruby-in-Ruby interpreter including Array/Hash/String as abstract ("Hollow") classes, an undo queue, a statistical time-profiler, an event loop, a modular marshaller ("ToSource"), a specification for a modular+reflexive+homoiconic remote call system ("LGRAM"), a declarative type system, a schema for expressing Ruby source code as proper (non-special) Ruby objects, etc.
Marathon is a GUI test tool that allows you to play and record scripts against a Java Swing UI. It's written in Java, and uses Python and Ruby as its scripting language (the emphasis being on an extremely simple, readable syntax that customers/testers/analysts feel comfortable with). Marathon includes a recorder, editor, player, and debugger to simplify working with test scripts.
The JumpBox for Ruby on Rails is a self-contained Ubuntu Linux environment that, upon startup, immediately hosts fully functioning Apache, Ruby, MySQL, and Ruby On Rails environments. With only a minimal amount of preparation, you can use your favorite deployment method to install and host your Rails application on the JumpBox.
tuitest is a tool to create and run automated tests of text user interfaces. It is meant as a complement to the widespread use of unit tests, and uses concepts known from GUI testing tools with the difference that it applies them specifically to text- and terminal-based user interfaces. It consists of a recorder that records the interaction with an application under tests and generates a Ruby script that replays the same interaction, optionally with the same timing. Ruby replaying is supported through a native Ruby module.